They were relatively popular here. The choices at the time were the Bell (no style points, but I wore it), Skid-lid which I thought looked pretty cool, the MSR (Mountain Safety Research) helmet that my wife wore and looked like a mountaineering helmet, and the ProTec, which looked like a detuned hockey helmet. The Skid-lid was fiberglass shelled, which some thought provided maximum protection, the nay-sayers argued that the gaps allowed you head to be exposed to sharp objects like branches and handlebars. If you really want to know what the head-gear mentality was back then, leather hair-nets still met the helmet requirement for USCF racing. Most racers trained bare-headed and only used head-gear because it was required for racing.
Kevin Ko
Eugene